Powering Europe - European Wind Energy Association

connectingwindpowertothegrid
futuredevelopments
As noted above, technical requirements may well become
more onerous for wind generation as wind power
penetration levels increase in the future.
One possible new requirement is for an inertia function.
The spinning inertias in conventional power plants
provide considerable benefits to the power system by
acting as a flywheel, and thereby reducing the shortterm
effects of imbalances of supply and demand.
Variable speed wind turbines have no such equivalent
effect, but in principle their control systems could provide
a function which mimics the effect of inertia.
There may also be a move towards markets for services,
rather than mandatory requirements. This would
be economically more efficient, as the generator best
able to provide the service will be contracted to provide
it. For example, if a wind power plant provides a
useful service to the network operator in controlling
voltages, i.e. it does more than just correct its own
negative effects, then the wind power plant should be
paid for this service. Whether this is cheaper than other
options available to the network operator should be
determined by the market. Moreover, due to the power
electronics in electrical conversion systems, wind power
plants can provide some network services, especially
voltage control, more rapidly than conventional
thermal plants.
2.3 Two-step process for grid
code harmonisation in Europe
There is considerable potential for improving the process
of wind power integration by harmonising grid
codes requirements for wind power. Such a process
will benefit all the stakeholders involved in the integration
of wind power. A systematic approach to setting
a European grid code harmonisation process in
motion was proposed by EWEA in 2008 15 . Harmonisation
does not automatically mean that the maximum
60
and most stringent requirements should apply everywhere,
rather it is a process of cleaning out technically
unjustified requirements and creating a transparent,
understandable, comprehensive and well-defined set
of requirements according to common definitions and
specifications and optimised to the power systems
where they apply.
A two-step harmonisation strategy introduced by EWEA
consists firstly of a structural harmonisation, and secondly
a technical harmonisation. Together, the two
forms of harmonisation should particularly benefit
those system operators that have not yet developed
their own customised grid code requirements for windpowered
plants.
Structural harmonisation consists of establishing a
grid code template with a fixed and common structure
(sequence and chapters), designations, definitions,
parameters and units. The key aim of the structural
harmonisation process is to establish an accepted
framework for an efficient grid code layout. Such a
template was launched 16 by EWEA in 2009.
Technical harmonisation can be seen as a more longterm
process which works by adapting existing grid
code parameters following the template of the aforementioned
new grid code. The process is to be implemented
through co-operation between TSOs (ENTSO-
E), the wind power industry and regulatory bodies
(ACER). The implementation of the Third Liberalisation
package as described below provides the proper enabling
legal and institutional framework at EU level.
europeandevelopmentsatowardseuropeancode
In the developing European internal electricity market,
national networks have to be interlinked in a more efficient
way. They must be operated as part of an integrated
European grid to enable the necessary cross
border exchanges. This requires harmonised codes
and technical standards, including grid connection requirements.
However, the national power systems in
Europe today are so different that a full harmonisation
cannot and should not be carried out straight away.
15 http://www.ewea.org/fileadmin/ewea_documents/documents/publications/position_papers/ 080307_WGGcr_final.pdf
16 http://www.ewea.org/fileadmin/ewea_documents/documents/publications/091127_GGcF_ Final _Draft.pdf
Powering Europe: wind energy and the electricity grid